A machine that performs tasks, such as mathematical calculations or electronic communication, under the control of a set of instructions called a program is a computer. Programs usually reside within and are retrieved and processed by 's electronics, and the program results are stored or routed to output devices, such as video display monitors or printers. Computers are used to perform a wide variety of activities with reliability, accuracy, and speed.
Uses of Computers
People use computers in a wide variety of ways. In business, computers track inventories with bar codes and scanners, check the credit status of customers, and transfer funds electronically. In homes, tiny computers embedded in the electronic circuitry of most appliances control the indoor temperature, operate home security systems, tell the time, and turn videocassette recorders on and off. Computers in automobiles regulate the flow of fuel, thereby increasing gas mileage. Computers also entertain, creating digitized sound on stereo systems or computer-animated features from a digitally encoded laser disc. Computer programs, or applications, exist to aid every level of education, from programs that teach simple addition or sentence construction to advanced calculus. Educators use computers to track grades and prepare notes; with computer-controlled projection units, they can add graphics, sound, and animation to their lectures. Computers are used extensively in scientific research to solve mathematical problems.
How Computers Work
The physical computer and its components are known as hardware. Computer hardware includes the memory that stores data and instructions; the central processing unit (CPU) that carries out instructions; the bus that connects the various computer components; the input devices, such as a keyboard or mouse, that allow the user to communicate with the computer; and the output devices, such as printers and video display monitors, that enable the computer to present information to the user. The programs that run the computer are called software. Software generally is designed to perform a particular type of task. It prompts the user for input and commands, reports the results of these commands and other operations, stores and manages data, and controls the sequence of the software and hardware actions. When a computer boots up, it looks for the first thing in memory that it can find, this is usually called the operating system(CMOS). When the user requests that a program run, the operating system loads the program in the computer's memory and runs the program.
Input devices, such as a keyboard or mouse, permit the computer user to communicate with the computer. Other input devices include a joystick, a scanner, a light pen, a touch panel, and a microphone. Once the CPU(Central Processing Unit) has executed the program instruction, the program may request that information be communicated to an output device, such as a video display monitor or a flat liquid crystal display. Other output devices are printers, overhead projectors, VCRs, and speakers.
To process information electronically, data are stored in a computer in the form of binary digits, or bits, each having two possible representations (0 or 1). If a second bit is added the number of representations is doubled, resulting in four possible combinations: 00, 01, 10, or 11. A third bit is added and again doubles the number of combinations, resulting in eight possibilities: 000, 001, 010, 011, 100, 101, 110, or 111. Each time a bit is added, the number of possible patterns is doubled. Eight bits is called a byte; a byte has 256 possible combinations of 0s and 1s. A byte is a useful quantity in which to store information because it provides enough possible patterns to represent the entire alphabet, in lower and upper cases, as well as numeric digits, punctuation marks, and several character-sized graphics symbols, including non-English characters such as p. A byte also can be interpreted as a pattern that represents a number between 0 and 255. A kilobyte-1000 bytes-can store 1000 characters; a megabyte can store 1 million characters; and a gigabyte can store 1 billion characters. This memory is contained on the Hard Drive of the system and can be read and altered. The physical memory of a computer is either random access memory (RAM), which can be read or changed by the user or computer, or read-only memory (ROM), which can be read by the computer but not changed.
Earlier Computer Problems
Computers were definantely the most creative and useful inventions known to man. But they weren't great from the start, they had problems that they had to overcome. The earlier computers were run with tubes, they worked hard and were also great heat conductors, as a result they would ...